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Cotesia (=Apanteles) glomerata
Cotesia glomerata was introduced to North America in 1883 for the control of the imported cabbageworm on cole crops and has become a major mortality factor of cabbageworm.
Appearance Cotesia adults are small (about 7 mm), dark wasps and resemble flying ants or tiny flies. They have two pairs of wings, the hindwings being smaller than the forewings, and chewing-lapping mouth parts. The antennae are about 1.5 mm long, and curved (not elbowed) upward. The abdomen of the female narrows to a downward curving extension called the ovipositor with which she lays eggs. The pupae are in an irregular mass of yellow silken cocoons attached to the host larva or to plant leaves.
Habitat (Crops) Cole crops.
Pests Attacked The imported cabbageworm and its relative Pieris brassicae.
Life Cycle Adults mate and the females lay eggs, in most cases, immediately after emerging from their cocoons. Eggs are deposited into larvae (preferably first instar) of caterpillars--about 20-60 per larva--soon after mating. A female lays about 150-200 eggs during her life. Cotesia larvae emerge after about 15-20 days and spin their cocoons on or near the host which dies when the wasps emerge. The life cycle, from egg to adult, is approximately 22-30 days, depending on the temperature.
Pesticide Susceptibility In studies C. glomerata has been shown to be susceptible to several pesticides commonly used on cole crops.
Relative Effectiveness In the early season, parasitism by C. glomerata is low. However, numbers increase as the year progresses. By midseason, about half of imported cabbageworm larvae are parasitized, and late in the growing season, that percentage has increased to 60-75%. In addition, C. glomerata may be an important vector in the transmission of the granulosis virus in imported cabbageworm. It is resistant to attack by many hyperparasitoids.
Conservation Follow integrated pest management guidelines as presented in the tutorial of this guide.
Commercial Availability Cotesia glomerata is not available commercially at this time.
Acknowledgements: Thanks to Saskya Daly van Nouhuys, Department of Entomology, Cornell University, for providing material and for reviewing and making suggestions which have improved this section. References Hamilton, A.G. (1935) Miscellaneous observations on the biology of Apanteles glomeratus L. (Braconidae). Entomol. Monthly Mag., 71: 262-270. Hamilton, J.T. and Attia, F.I. (1975) The susceptibility of the parasite Apanteles glomeratus (L.) (Hym.: Braconidae) to insecticides. J. Entomol. Soc. of Australia, 9: Levin, D.B., Laing, J.E., Jaques, R.P. and Corrigan, J.E. (1983) Transmission of the granulosis virus of Pieris rapae (Lepidoptera: Pieridae) by the parasitoid Apanteles glomeratus (Hymenoptera: Braconidae). Environ. Entomol., 12: 166-170. McDonald, R.C. and Kok, L.T. (1991) Hyperparasites attacking Cotesia glomerata (L.) and Cotesia rubecula (Marshall) (Hymenoptera: Braconidae) in southwestern Virginia. Biol. Control, 1: 170-175. Matheson, R. (1907) The life-history of Apanteles glomeratus, L. Can. Entomol., 39: 205-207.
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